Regarding nuclear reactions that release a great deal of energy,
which statement is true?
A. In a fission chain reaction, a uranium nucleus struck by a
high-energy neutron emits two neutrons.
B. Nuclear fission releases more energy per unit mass than
does a fusion reaction.
C. Nuclear reactors produce dangerous levels of air pollution.
D. A fusion reaction proceeds through the joining of two
isotopes of hydrogen
I think it's D
To determine which statement is true regarding nuclear reactions that release a great deal of energy, let's analyze each statement:
A. In a fission chain reaction, a uranium nucleus struck by a high-energy neutron emits two neutrons.
This statement is true. In a fission reaction, a uranium nucleus can absorb a neutron, become unstable, and then split into two smaller nuclei, releasing a large amount of energy. During this process, additional neutrons are usually emitted, and they can go on to induce fission in other uranium nuclei, leading to a chain reaction.
B. Nuclear fission releases more energy per unit mass than does a fusion reaction.
This statement is also true. Nuclear fission reactions typically release significantly more energy per unit mass compared to fusion reactions. Fission reactions involve the splitting of heavy atomic nuclei, such as uranium or plutonium, whereas fusion reactions involve the merging of lighter atomic nuclei, such as hydrogen isotopes. While fusion reactions release vast amounts of energy, they typically require higher temperatures and pressures to initiate and sustain compared to fission reactions.
C. Nuclear reactors produce dangerous levels of air pollution.
This statement is false. Nuclear reactors themselves do not produce air pollution in the form of greenhouse gases or other harmful emissions. However, the production, mining, and processing of nuclear fuel can have associated environmental impacts if not managed properly. The issue of nuclear waste disposal also needs careful consideration to prevent any potential hazards.
D. A fusion reaction proceeds through the joining of two isotopes of hydrogen.
This statement is true. In a fusion reaction, lighter atomic nuclei combine to form a heavier nucleus, releasing a significant amount of energy. One common example of a fusion reaction involves the isotopes of hydrogen, deuterium (^2H) and tritium (^3H). When these isotopes fuse under high temperature and pressure, they form helium and release a substantial amount of energy.
Based on the analysis, statement A and statement D are both true. The correct answer depends on the desired statement in the question.